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# voltage drop calculations

#1
09-26-18, 05:17 PM
Member
Join Date: Sep 2018
Location: usa
Posts: 3
voltage drop calculations

I had power dropped on my property and it is 350' to our build site. I want 200amp service at the house. what is my voltage drop going to be for the long run to the house, and what are the potential hazards for such drop? I had planned on running aluminum 4/0 4/0 2/0. I found an online calculator that indicated my voltage drop would be 2.86% based on 240v, AC single phase, single set of conductors at a load current of 200 amps. Do I need to worry about this? Should I have the power company move my meter base next to the house?

#2
09-26-18, 05:31 PM
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Join Date: Mar 2010
Location: USA
Posts: 4,109
The 2.86% voltage drop at 200 amps is not a problem.

Your choice, probably depending on cost. You would have to pay for the line from the present proposed meter location over to the new meter base at your house plus a separate pole transformer nearby. This line would be a medium tension (primary) line to eliminate the voltage drop problem.

Otherwise the long fat 120/240 volt line you first suggested has no greater hazard compared with a shorter skinnier line carrying the same voltage in the same manner (underground; overhead). If there is a whole house disconnect switch or breaker out at the meter base then you need a fourth conductor for ground running to the house panel regardless of distance.

#3
09-26-18, 05:46 PM
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Join Date: Sep 2018
Location: usa
Posts: 3
Thanks. I am assuming I had all my factors correct that I plugged into the online calculator, and if so i take it the 6.86v drop is nothing to worry about. I forgot to mention I would pull a ground wire as well.

#4
09-26-18, 06:33 PM
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Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 13,638
Your load will not be 200 amps, that is the max rating of the breaker. You need to do a load calculation to determine the load that will be on the feeder. Voltage drop is calculated by voltage, current, distance, and wire material.

#5
09-26-18, 10:20 PM
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Join Date: Sep 2018
Location: usa
Posts: 3
Thank you, based on a formula I found online my load current came out to about 120 amps. that puts my voltage drop at 2.7%. We have no furnace, use wood heat, and my water pump runs off solar power. Oven / stove are gas, biggest appliance is water heater and dryer.

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